In the prior art, seals are used inter alia for the securing of closures. A simple and widely used example is represented by wire loops whose ends are connected with a sealing element, so that opening the seal without destroying the wire loop or seal is not possible. In the field of medical science, seals are used for instance with sterile containers in order to be able to check if such a sterile container has already been opened once after the sterilization and if instruments contained therein are still sterile. Various types of seals are known for this.
A very simple, known seal for sterile containers works according to the principle of a cable tie, i.e. a loop made of plastics, which is put through eyes provided on a container lid and a container trough and then closed. A proximal end of the seal is provided with indentations whose flanks pointing toward the proximal end are slanted, while the flanks pointing toward the distal end are set with a steep angle. The other, distal end of the seal is provided with a head having a through-hole into which an elastic latching nose projects. The seal is closed by inserting its proximal end into the through-hole such that the latching nose latches in place in one of the indentations. Due to the steep flank angle and a corresponding configuration of the latching nose, it is easy to insert the proximal end of the seal into the through-hole, but pulling it out in the reverse direction is not possible. The seal may be provided with labeling fields or the like.
Such a seal can only be opened by destroying it, i.e. by severing it at a certain position. The problem is that they are not protected from willful manipulations. A thin object could be pushed into the head of the seal, deforming the flexible latching nose against the spring action and opening the seal without destroying it. Thereafter, it could even be reused, so that it is not able to fulfil its function of ensuring the original state. In the clinic field, there is the further problem that a properly opened seal, i.e. a destroyed seal, loosely hangs on the container and can fall off during opening the container. As the floor of a surgery room is usually not sterile, a seal which has fallen down cannot be picked up just like that. As it is quite common that several containers are used, it might happen that several seals fall to the floor and impair the safe standing, walking and hence the concentration of the staff.
Another security system for sterile containers is made up of a bendable card which is put from the side into a slit of the container, so that its free end comes to lie in front of the closure tab of the container lid. The inserted end of the card has cutouts which will be engaged by associated protrusions in the slit. This is why the card cannot be removed from the slit if the container is closed. During opening the closure tab, the card is bent and springs back into its original position behind the closure tab. If the closure tab is closed again, the card is situated behind the closure tab and not in front of it, being indicative of the container already having been opened already. A disadvantage of this safety system is that the mechanism allowing the replacement of the card for a successive sterilization procedure is relative complicated, hence expensive and prone to failure and has a negative effect on the sterilization result. What is more, also this safety means is not tamper-proof. With the help of a long, thin object, the card could be bent away prior to closing the closure tab again, so that it will be again situated in front of the closure tab.
A further problem of the previously known seals and safety mechanisms is that it is not readily possible to see at the first glance whether they are already devaluated or destroyed or not. For example with a seal in a looped shape, a destroyed seal can be threaded again into the eyes on the container and an inattentive user will not necessarily notice that the eye has been destroyed already and hence devaluated.
DE 10 2012 004 961 A1 discloses a security seal comprising a seal foot having at least one latching protrusion and a seal head connected with the seal foot and having at least one locking tab. Each of the locking tabs is movably connected with the seal head by means of at least one hinge element. The seal foot comprises latching protrusions elastically formed thereon, which engage correspondingly formed latch structures during attaching the seal on a container and fix the seal on the container. With such a seal, it is not necessarily ensured that the seal is in its correct position and has been undetachably attached on the container. By way of example, the seal may seemingly latch in place on the container or be locked on the latter if it is attached to it in a tilted fashion, without the latching protrusions of the seal indeed having undetachably engaged the latch structure. In this case, the container is only apparently sealed in the correct manner, but can be opened without the possibility of detecting the manipulation. Furthermore, a seal might be potentially used again after the first use, impairing the tamper protection of the system.